Control devices for components such as wireless thermostat controllers or wireless light switches require the use of control circuitry that can operate for long periods of time on a single battery. These types of circuits have long sleep periods wherein minimal power is needed to operate the circuit thus providing a minimal draw on the battery charge. These circuits have very short periods of time when control operations require higher voltage levels in order to accomplish various procedures. In order for these types of circuits to have the necessary operating characteristics, improved circuitries must be provided which will provide optimal power characteristics in both the high power usage and low power usage modes of operation. These types of circuitries also require some type of power control logic enabling ease of switching between these modes of operation having different power usage characteristics.
The Real time clock (RTC) of this type of power control circuit is required to work with a low bias current. However, with transistor processes variation, resistor processes variation and transistor mismatch, the current in the RTC can vary from −40% to +50% in the worst corners. To control the current in the RTC in a tighter range, and ensure that RTC bias current can be set to the lowest possible value which guarantees operation under all operating conditions, a system and method is needed to reduce the RTC bias current and the potential current variation over a volume of devices.